1. Technical Field
The present disclosure relates to a circuit breaker of a gas-insulated switchgear, and more particularly, to a self-blast circuit breaker of a gas-insulated switchgear, which reuses arc heat.
2. Related Art
A gas-insulated switchgear (GIS) refers to a switching system in which switching units such as a circuit breaker and a disconnecting switch, a transformer, a lightning arrestor, a main bus bar, and so on are collectively received in a metal tank, charging parts are supported by spacers, an SF6 gas as an insulation medium with excellent insulation and arc extinction performance is filled in the interior of the tank, and the tank is then sealed.
The main pressure-resistant components of the GIS include a gas circuit breaker, an earthing switch, a lightning arrestor, a potential transformer, a current transformer, and so forth.
The operating duties of the circuit breaker used in a GIS are specified in the IEC standard. In general, the rated operating sequence of ‘O-0.3s-CO-3 min-CO’ is observed.
Basically, in a circuit breaker, interrupting performance is required two times within 0.3 second. Since a first interruption duty is performed in the state in which the SF6 gas is in a cool gas state, the interrupting performance is excellent. Upon interruption, the temperature of the surrounding SF6 gas rises to 20,000° C. to 30,000° C. within a short time by a generated arc. A second interruption duty after 0.3 second is performed in the state in which the interior of the circuit breaker has a high temperature and a high pressure. Since the interrupting performance of the SF6 gas at the high temperature is abruptly degraded, it is difficult to interrupt fault current.
A related art is disclosed in Korean Unexamined Patent Publication No. 10-2012-0002779 (published on Jan. 9, 2012) entitled ‘Self-blast interrupter of gas-insulated switchgear’.